The laying of pipe under water or on land according to present methods presents some serious problems. According to present methods, pipe joints 40 feet in length, or sometimes twice or three times that length, are welded together end-to-end as the laying of a pipeline proceeds. The welding of the end-to-end pipe joints is troublesome because before welding the pipe ends must be prepared by beveling or machining and the pipe joints must be aligned, made circular and abutted in preparation for welding. When the pipe laying is done from a moving or movable vehicle or support, the motion of the vehicle or support causes problems. These problems are severe when pipe laying is done from a floating vessel, such as a lay barge, because the vessel is moved by the water movement and wind as well as by the travel movement of the vessel. When the pipeline is made up of individual lengths of pipe, the vessel or other carrier must be stopped and started for addition of each length or joint of pipe. This involves trouble of control, and adds to the utilization of power and increases cost.
When pipe is laid from a movable vessel or vehicle, the pipeline behind the vehicle is fixed in place while the vessel or vehicle is moving, and it is necessary to adjust the pipe tension as it leaves the carrier in order to prevent damage to the pipe and to the apparatus and carrier. Therefore, complex and expensive pipe tensioning apparatuses must be used in conjunction with the pipe laying. Many other serious problems, known in the art, are encountered in connection with the laying of pipe from a moving vessel, vehicle or other movable supporting structure.